Yeast experiment suggests rapid start for multicellular life

An experiment to try and better understand the initial evolutionary process in single-celled microbes clumping together to create multicellular entities has taken place in a laboratory at the University of Minnesota.

Using brewer’s yeast cells, biologists found they can evolve into primitive bodies in about two weeks. Evolutionary biologists have struggled to understand the transition to multicellular life. The human body today has more than 200 types of cells and our ancestors were single-celled microbes for about three billion years before they evolved bodies.

Bearing in mind the demands for cooperation and sacrifice our 100 trillion or so cells in our bodies are put through in a lifetime, it should make it challenging and difficult for single-celled life to become multicellular, reports the New York Times.

It has often been a mystery to evolutionary biologists why it has not seemed difficult for animals, plants and other life forms to have evolved bodies.

William Ratcliffe, a research postdoctorate at the University said:

We know that multicellularity has evolved in different lineages at least 25 times in the history of life.

Dr. Ratcliff and his adviser, Michael Travisano, are experimental evolution experts who experiment with microbes that can evolve into interesting new traits within weeks. Their experiment with brewer’s yeast, which normally lives as single cells, feeding on sugar and budding off daughter cells to reproduce is a clear hint of faster evolution from single cells.

It took just weeks for Dr. Ratcliffe to observe his yeast had formed a cloudy layer at the bottom of his flasks. Inside that cloud was a yeast no longer growing as single cells. In fact the soupy layer was forming snowflake-shaped clusters of hundreds of cells fused together.

A paper (opens as a pdf document) will be published this week in the National Academy of Sciences in the USA, detailing the experiment and its findings.